The present invention relates to an agricultural row marker. A row marker is a device which is used with a row crop planter and extends to the side of the planter to mark the center of the next swath to be planted. For example, in the case of an 8-row planter, and assuming that the land to the left of the tractor operator has already been planted, while the farmer is planting a swath of eight rows, a marker is extended to the right of the planter to provide a small furrow marking the center of the next swath to the planted. When the farmer has planted the current swath, he sights on the furrow previously marked and centers his tractor on it when planting the next swath.
As tractors and planting equipment have gotten larger through modern technology and a desire to plant crops faster, so have the length of marker arms become greater. Typically, a marker will have two separate sections pivoted in the middle which extend and are generally aligned in the unfolded or use position, but which fold when not in use and are stored above the mounting bar of the planting frame. These markers can be quite heavy, and they are normally actuated between the use and storage positions by means of an hydraulic cylinder.
During a folding sequence, as the weight of the marker passes over top dead center, there is a tendency for it to fall slightly as the force on the cylinder rod changes from compression to tension. With the weight of the marker arm added to the extension force of the cylinder, as the marker arm approaches the storage position, there is a tendency for it to slam against its rest or stop. Not only is the noise undesirable on the part of the farmer, but depending upon the size and weight of the marker arm and the resulting closing force, the marker arm could be bent or damaged after a number of closing sequences have been encountered. It is thus a primary objective of the present invention to provide an agricultural row marker which decelerates as it approaches the storage position to avoid slamming the marker arm against its rest or stop.
In order to accomplish this, the present invention provides a swing link which is pivotally mounted to the planter frame mount, and which guides the rod end of the hydraulic cylinder about the pivotal connection between the base of the marker arm and the frame. A second link, sometimes referred to as a "push/pull" link, has one end connected to the swing link adjacent the cylinder rod, and the other end pivotally connected to the base of the marker arm.
With the hydraulic cylinder retracted, the push/pull link is generally aligned with the axis of the cylinder and is pushed by it, and in turn pushes the base of the marker arm about its pivotal connection to the frame. During the initial extension motion of the hydraulic cylinder, equal increments of elongation of the cylinder cause generally equal angular displacements or rotation of the marker arm. This is desirable in order to have a rapid motion in lifting the marker arm as well as in placing it near the ground at the end of a sequence extending it to the use position.
As the marker arm passes over top dead center toward the storage position, the push/pull link is placed in tension, holding the marker arm against its weight. The swing link continues to guide both the rod end of the cylinder and the push/pull link.
As the the marker arm approaches the storage position, the push/pull link is rotated to a position such that equal increments of extension of the cylinder cause progressively smaller increments of angular displacement of the marker arm, thereby causing the marker arm to decelerate as the cylinder reaches the end of an extension sequence. This action prevents slamming of the marker arm against its stop or rest, and avoids the above mentioned disadvantages that would otherwise occur if the slamming action were not avoided.
Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment where identical reference numerals will refer to like parts in the various views.